This invention relates in general to an electronic tracking system suitable for use in a mail sorting machine to monitor and control the movement of an envelope through the machine to thereby direct this envelope to its designated sort bin. In particular, the electronic tracking system of the present invention is comprised of a plurality of electronic tracking circuits which are interconnected in series. These circuits cooperate with each other to transfer a coded bin designation signal between them in synchronization with an envelope moving through the machine.
The volume of mail handled daily by large businesses, institutions and governmental entities has reached the point where new techniques and machines for automatically handling and sorting this mail more efficiently and economically must be developed. Although several machines for handling and sorting mail are presently available, there prior art machines have not proven to be satisfactory for several reasons. For example, the presently existing mail sorting machines are normally very complex in design and operation. These machines are typically comprised of an array of metal bands which form a plurality of guideways for transferring envelopes from a central sorting location to one of the machine's sort bins. In these machines, the incoming envelopes are initially separated and successively provided to a read station where the designated sort bin for each envelope is ascertained. The envelope is then introduced into the guideway corresponding to its designated bin for transfer to this bin. This type of mail sorting machine requires the use of a complex sorting mechanism for introducing an envelope into its appropriate guideway. The complex nature of the sorting mechanism tends to slow down the sorting operation performed by this type of machine, due to the complex physical action needed to introduce an envelope into the appropriate guideway. In addition, these prior art mail sorting machines are not very reliable and tend to bend, crumble, tear or otherwise damage the envelopes they handle. Another problem associated with these mail sorting machines is that they have a tendency to direct an envelope to the wrong sort bin.
The electronic tracking system of the present invention, however, may be incorporated into a mail sorting machine to provide a much simpler technique for handling mail within the machine. In particular, this electronic tracking system makes it possible to replace the above described plurality of guideways with a single guideway which is formed by a plurality of deflecting gates. These deflecting gates are arranged in pairs with each pair of gates being aligned to provide a channel through which an envelope may be conveyed.
The electronic tracking system is comprised of a plurality of individual tracking circuits which are connected in series. One of these tracking circuits is associated with each pair of deflecting gates to control the position of these gates. These tracking circuits operate in combination with strategically placed envelope sensors to monitor the movement of an envelope through the machine and to control the transfer of a coded bin designation signal between them in synchronization with the movement of the envelope to which the signal applies. In particular, each tracking circuit is provided with an associated envelope sensor which is properly positioned to alert its associated tracking circuit of an approaching envelope.
Upon receipt of an alert signal from its associated envelope sensor, the tracking circuit acquires from an anteriorly positioned portion, the coded bin designation signal presently stored therein and generates a clear signal which is provided to its anteriorly positioned tracking circuit to clear the coded bin designation signal presently stored with this circuit. The coded bin designation signal is assembled to have a location portion which is comprised of a binary coded number representative of a particular pair of sort bins and a bin digit which is an individual bit having a logic state representative of one of the bins of the designated pair.
The coded bin designation signal is transferred between tracking circuits such that the present numerical value of the location portion of the signal is transferred intact if the numerical value of this portion of the signal is below a preselected maximum number. If, on the other hand, the numerical value of the location portion of the coded designation signal is equal to the preselected maximum number, the coded bin designation signal is transferred to the next tracking circuit such that the location portion of the signal assumes a count state of zero.
Upon receipt of a coded bin designation signal, the tracking circuit immediately increments the binary coded number which comprises the location portion of the signal by a set amount and then compares the resulting binary number with a preselected maximum number to determine if they coincide. If the incremented portion of the coded bin designation signal does not coincide with the preselected maximum number, the position of each of the deflecting gates associated with this tracking circuit is unchanged thereby allowing the envelope to pass through the channel formed by these gates unimpeded. However, the incremented portion of the coded bin designation signal is equal to the preselected maximum number, the tracking circuit checks the logic state of the bin digit to determine which of the deflecting gates is to be activated. The tracking circuit then activates the solenoid corresponding to the designated deflecting gate causing this gate to be moved into the channel to divert an advancing envelope into the sort bin associated with this gate. The tracking circuit keeps this solenoid in an active condition until a clear signal is received from the posteriorly positioned tracking circuit. Since the location portion of the coded designation signal now has a numerical value equal to the preselected maximum number, the location portion of the coded bin designation signal is transferred to the posteriorly positioned tracking circuit and then increments the location portion of this signal and stores it until a subsequent envelope causes a new coded bin designation signal to be sorted in this circuit.
It is therefore an object of the present invention to provide an electronic tracking system which may be incorporated into a mail sorting machine to simplify the design and operation of the machine and the technique for directing an envelope to its designated sort bin.
Another object of the present invention is to provide an electronic tracking system which is suitable for monitoring and controlling the movement of an envelope through a mail sorting machine having a plurality of deflecting gates which are arranged in pairs to provide a single channel through which mail may be transferred to the machine's various sort bins.
A further object of the present invention is to provide an electronic tracking system of the character described which is comprised of a plurality of tracking circuits connected in series to transfer between them a coded location signal in synchronization with the movement of an envelope through the machine.
An additional object of the present invention is to provide an electronic tracking system of the character described which is capable of simultaneously controlling the position of two separate deflecting gates.
It is another object of the present invention to provide an electronic tracking system of the character described which is capable of accomodating envelopes of varying lengths without requiring any change in its internal components.
It is yet another object of the present invention to provide an electronic tracking system of the character described which may be used in mail sorting machines of differing operating speeds without requiring a change in any of the circuit's internal components.
It is an additional object of the invention to provide an electronic tracking system which is capable of reliable operation even if an envelope is improperly removed from the channel through which it is being conveyed to the sort bins.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.